PHP递归创建多级目录,php递归
PHP递归创建多级目录,php递归
我的第一个感觉就是用递归创建,具体思路如下:
function Directory($dir){ if(is_dir($dir) || @mkdir($dir,0777)){ //查看目录是否已经存在或尝试创建,加一个@抑制符号是因为第一次创建失败,会报一个“父目录不存在”的警告。 echo $dir."创建成功<br>"; //输出创建成功的目录 }else{ $dirArr=explode('/',$dir); //当子目录没创建成功时,试图创建父目录,用explode()函数以'/'分隔符切割成一个数组 array_pop($dirArr); //将数组中的最后一项(即子目录)弹出来, $newDir=implode('/',$dirArr); //重新组合成一个文件夹字符串 Directory($newDir); //试图创建父目录 if(@mkdir($dir,0777)){ echo $dir."创建成功<br>"; } //再次试图创建子目录,成功输出目录名 } } Directory("A/B/C/D/E/F");
输出结果如图:
但是可以看得出来,写得也太麻烦了,在手册里翻看文件函数,看到一个dirname()函数,其原型如下:
string dirname ( string $path )
给出一个包含有指向一个文件的全路径的字符串,本函数返回去掉文件名后的目录名。
在 Windows 中,斜线(/)和反斜线(\)都可以用作目录分隔符。在其它环境下是斜线(/)。
可以稍稍地优化一下:
function Directory($dir){ if(is_dir($dir) || @mkdir($dir,0777)){ echo $dir."创建成功<br>"; }else{ Directory(dirname($dir)); if(@mkdir($dir,0777)){ echo $dir."创建成功<br>"; } } }
效果一样。
之后我在在网上搜一下答案,找到一个异常精辟的:
function Directory( $dir ){ return is_dir ( $dir ) or Directory(dirname( $dir )) and mkdir ( $dir , 0777); }
现在来解释一下整个函数:
先介绍一下PHP中逻辑运算符的优先级顺序:&& > || > and > or,即符号型>字母型,AND型>OR型,所以函数体可以看成:
is_dir ( $dir ) or (Directory(dirname( $dir )) and mkdir ( $dir , 0777));
先判断目标目录是否存在,若存在,依or的短路特性,后面的整体被短路,跳过执行;若目标目录不存在,则执行后面的函数体:
Directory(dirname( $dir )) and mkdir ( $dir , 0777)
我考虑了一下先进行递归的用意:先执行递归,意在确认其父目录(dirname($dir))都已经创建完毕,使后面的mkdir()函数不会创建子目录时找不到父目录发出警告。
进入递归深处后,确认最深处的根目录存在后,从根目录向下依次创建目录。
最后,建议要找工作的亲们,去网上找些大公司面试题做一下,毕竟他们考得较为综合较深,在学习知识的时候,也刷一下题,另外也一定要做一下,因为很容易眼高手低,一开始的函数,我优化了好几遍才能正常使用。
这就是一道PHP递归创建多级目录面试题目,以后小编会再找些有意思的面试题跟大家分享。

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